Pd/C: An efficient, heterogeneous and reusable catalyst for phosphane-free carbonylative suzuki coupling reactions of aryl and heteroaryl iodides

Article abstract of DOI:10.1002/ejoc.201001134

The carbonylative Suzuki coupling reaction of aryl boronic acid with different aryl and heteroaryl iodides was carried out to synthesize various unsymmetrical biaryl ketones by using Pd/C as an efficient, heterogeneous and reusable catalyst. The catalyst exhibits remarkable activity, and its reusability was tested up to four consecutive cycles. The reaction is applicable for various aryl and heteroaryl iodides having different steric and electronic properties. It provides good to excellent yield of the desired products. The developed protocol is advantageous with regard to the ease in handling the catalyst and the simple work-up procedure; it is also an environmentally benign process with effective catalyst recyclability. A facile protocol has been developed for the carbonylative Suzuki coupling reaction of aryl and heteroaryl iodides with Pd/C as effective, heterogeneous, reusable catalyst. The system is applicable for a wide variety of aryl and heteroaryl iodides. Copyright

Full text of DOI:10.1002/ejoc.201001134

FULL PAPER
DOI: 10.1002/ejoc.201001134
Pd/C: An Efficient, Heterogeneous and Reusable Catalyst for Phosphane-Free
Carbonylative Suzuki Coupling Reactions of Aryl and Heteroaryl Iodides
Mayur V. Khedkar,[a] Pawan J. Tambade,[a] Ziyauddin S. Qureshi,[a] and
Bhalchandra M. Bhanage*[a]
Keywords: Cross-coupling / Heterogeneous catalysis / Palladium / Phosphane ligands / Suzuki carbonylation
The carbonylative Suzuki coupling reaction of aryl boronic
acid with different aryl and heteroaryl iodides was carried
out to synthesize various unsymmetrical biaryl ketones by
using Pd/C as an efficient, heterogeneous and reusable cata-
lyst. The catalyst exhibits remarkable activity, and its reus-
ability was tested up to four consecutive cycles. The reaction
is applicable for various aryl and heteroaryl iodides having
different steric and electronic properties. It provides good to
excellent yield of the desired products. The developed proto-
col is advantageous with regard to the ease in handling the
catalyst and the simple work-up procedure; it is also an envi-
ronmentally benign process with effective catalyst recycl-
ability.
to air and moisture. After the first report of Suzuki, several
groups reported various protocols for the synthesis of such
biaryl carbonyl compounds. Various palladium-based cata-
lytic systems such as PdCl2(PPh3)2,[8] PdCl2(PPh3)2/
PdCl2(dppf),[9] Pd(OAc)2-imidazolium salts,[10] Pd(OAc)2/
N,N-bis(2,6-diisopropylphenyl)dihydroimidazolium chlo-
ride,[11] an MCM-41-supported bidentate phosphane palla-
dium complex,[12] Pd(OAc)2/di-1-adamantyl-n-butylphos-
phane[13] and Pd/thiourea,[14] have been used for this trans-
formation. However, despite their potential utility, the
above methods suffer from one or more drawbacks such
as the use of expensive, air/moisture sensitive phosphane-
donating ligands and difficulties associated with the separa-
tion of catalyst and product, which limit their applications.
Also, in many cases the catalysts used are homogeneous,
and hence they are not recyclable. The loss of a palladium
catalyst, even at ppm level, is not desirable because of its
high cost and toxicity for pharmaceutical applications.
Therefore, the search for a heterogeneous and reusable cata-
lyst that could efficiently catalyze the carbonylative Suzuki
coupling reaction without the aid of phosphane ligands is
the subject of the present work. Moreover, a literature sur-
vey reveals that Pd/C was found to be an effective catalyst
for the Suzuki–Miyaura reaction.[15] So, we chose Pd/C as
the best alternative for the carbonylative Suzuki coupling
reaction.
Introduction
Synthesis of biaryl and heteroaryl carbonyl compounds
has attracted considerable interest, as they are important
building blocks for various natural products (e.g. Cotoin,
Papaveraldine), biologically active compounds (e.g. Sup-
rofen, Ketoprofen) and pharmaceutical compounds.[1]
A
common route for the synthesis of biaryl ketones involves
Friedel–Crafts acylation of substituted aromatic ring com-
pounds with acyl halides,[2] which is incompatible with
many functional groups and requires over stoichiometric
amounts of Lewis acid; furthermore, the regioselectivity is
limited to the para position. Traditionally, biaryl ketones
were synthesized by transition-metal-catalyzed, three-com-
ponent, carbonylative cross-coupling reactions between or-
ganometallic reagents, carbon monoxide and aryl electro-
philes, which is now considered as a useful tool for synthesis
of a wide variety of carbonyl compounds. Various aryl
metal reagents like magnesium,[3] silicon,[4] aluminium[5]
and tin[6] have been reported. However, these carbonylative
cross-coupling reactions have several limitations due to the
formation of biaryl side products without carbon monoxide
insertion, particularly with electron-deficient aryl halides.
In 1993, Suzuki et al. reported a facile protocol for the
synthesis of biaryl ketones from carbon monoxide, aryl ha-
lide and aryl boronic acid by using palladium catalyst.[7] In
principle, this reaction provides a versatile tool for organic
synthesis, as boronic acids are generally nontoxic and stable
In continuation of our previous work on phosphane-free
carbonylation reactions,[16] herein we report an efficient
protocol for the carbonylative Suzuki coupling reaction of
aryl boronic acid with various aryl and heteroaryl iodides
with Pd/C as a heterogeneous and recyclable catalyst
(Scheme 1). The catalyst showed remarkable activity, and
the present system tolerates a wide variety of functional
groups such as –CH3, –OCH3, –NH2, –COCH3, –NO2
[a] Department of Chemistry, Institute of Chemical Technology
(Autonomous),
N. Parekh Marg, Matunga, Mumbai 400019, India
Fax: +91-22-24145614
E-mail: bhalchandra_bhanage@yahoo.com
bm.bhanage@ictmumbai.edu.in
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M. V. Khedkar, P. J. Tambade, Z. S. Qureshi, B. M. Bhanage
FULL PAPER
and –Br on both aryl boronic acid and aryl iodide. The Table 1. Effect of reaction parameters on the carbonylative Suzuki
coupling reaction of iodobenzene with phenyl boronic acid.[a]
catalyst was also found to be reusable for up to four consec-
Temperature (°C) Yield (%)[b]
utive cycles without any significant loss in activity.
Entry Solvent
Effect of solvent
Base
1
2
3
4
5
6
toluene
DMF
water
diisopropyl ether K2CO3
acetonitrile
anisole
K2CO3
K2CO3
K2CO3
100
100
100
100
100
100
76
10
25
74
18
90
K2CO3
K2CO3
Effect of base
7
8
9
10
11
12
anisole
anisole
anisole
anisole
anisole
anisole
Et3N
Cs2CO3
K3PO4
morpholine 100
piperidine 100
DBU
100
100
100
25
70
40
–
–
–
100
Effect of temperature
13
anisole
anisole
anisole
K2CO3
K2CO3
K2CO3
K2CO3
80
70
89
75
87
Scheme 1. Carbonylative Suzuki coupling reaction of aryl and het-
ero aryl iodides with aryl boronic acid.
14
120
100
100
15[c]
16[d] anisole
[a] Reaction conditions: iodobenzene (1 mmol), phenyl boronic
acid (1.2 mmol), 10% Pd/C (2 mol-%), K2CO3 (3 mmol), solvent
(10 mL), 8 h, CO pressure: 200 psi. [b] GC yield. [c] CO pressure:
100 psi. [d] Time: 6 h.
Results and Discussion
To optimize the reaction conditions, the carbonylative
cross-coupling reaction of iodobenzene with phenyl boronic
acid in the presence of Pd/C as a catalyst was chosen as a
model system. The influence of various parameters such as
The optimized reaction conditions were iodobenzene
solvent, base, temperature, CO pressure and time (Table 1) (1 mmol), phenyl boronic acid (1.2 mmol), CO pressure
were examined on the model reaction. The influence of sol- (200 psi), 10% Pd/C (2 mol-%), K2CO3 (2 mmol) in anisole
vents on the carbonylative Suzuki coupling reaction was in- (10 mL) at 100 °C for 8 h. These conditions were applied to
vestigated (Table 1, Entries 1–6). Solvents like toluene the coupling of a variety of phenyl boronic acids with a
(76%), N,N-dimethylformamide (10%), water (25%), di- range of aryl and heteroaryl halides. Various electron-
isopropyl ether (74%), acetonitrile (18%) and anisole (90%) donating and electron-withdrawing groups like –CH3,
were screened. It was observed that the reaction gave better –OCH3, –NO2, –Br, –COCH3, –NH2 on both aryl iodide
results with ethereal solvents like diisopropyl ether and an- and boronic acid smoothly undergo carbonylative Suzuki
isole. However, as the maximum yield of the desired prod- coupling, providing the desired biaryl ketones (Table 2).
uct was obtained with anisole, it was used for further stud-
Iodobenzene reacts efficiently with phenyl boronic acid
ies. It is well known that bases play a crucial role in cou- within 8 h, providing 90% yield of the desired product
pling reactions; hence we attempted the reaction in the pres- (Table 2, Entry 1). The carbonylative cross-coupling reac-
ence of various organic and inorganic bases (Table 1, En- tion of electron-donating substituents such as –CH3 and
tries 6–12). Among the various bases screened, inorganic –OCH3 at the para and ortho positions with phenyl boronic
carbonates such as K2CO3 and Cs2CO3 were found to af- acid went smoothly, providing good to excellent yields of
ford the desired product in good to excellent yields. The the expected product (85–93%) (Table 2, Entries 2–5). The
reaction using morpholine and piperidine yielded 75–85% reaction of aryl iodides bearing electron-withdrawing
of aminocarbonylated product instead of biaryl ketones. groups such as –NO2, –Br and –COCH3 also permits the
Thus, further reactions were carried out with K2CO3 as a carbonylative coupling reaction with phenyl boronic acid,
base.
giving the required products in moderate to good yields un-
In order to examine the effect of temperature, reactions der optimized reaction conditions (Table 2, Entries 6–8).
were carried out at different temperatures ranging from 80 The reaction of electron-rich ortho-iodoaniline with phenyl
to 120 °C (Table 1, Entries 6 and 13–14). It was observed boronic acid yields ortho-aminobenzophenone in moderate
that at 80 °C the yield of the desired product was low, amounts (83%, Table 2, Entry 9). The carbonylation of
whereas, on increasing the temperature up to 100 °C, 90% bulky 1-iodonaphthalene with phenyl boronic acid provided
yield of the product was obtained within 8 h. With further benzoyl naphthalene in 92% yield (Table 2, Entry 10). Next,
increase in temperature, no profound increase in the yield we investigated the effect of substituents on phenyl boronic
of the product was observed. The influence of CO pressure acid, both electron-donating and electron-withdrawing
and time were also studied, and the optimum pressure and groups were well tolerated under optimized reaction condi-
time were used for further studies.
tions. Phenyl boronic acids substituted with electron-donat-
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Pd/C: A Catalyst for Phosphane-Free Carbonylative Suzuki Coupling
Table 2. Carbonylative Suzuki coupling reaction of aryl iodides iodobenzene with p-bromophenyl boronic acid gave 70%
with various boronic acids.[a]
yield of the desired product under the optimized reaction
conditions (Table 2, Entry 14). Several groups such as Sas-
son and co-workers and Thathagar and co-workers have re-
placed expensive aryl iodide by aryl bromides or chlorides
in various C–C coupling reactions;[17–18] however, these pro-
tocols do not provide satisfactory yields in our case.
For generality, we extended our protocol to heteroaryl
iodides such as 2-iodopyridine, 3-iodopyridine, 2-iodothio-
phene, 5-iodoindole and 3-iodoquinoline (Table 3, Entries
1–14). The reaction of various heteroaryl iodides with dif-
ferent phenyl boronic acids gave good to excellent yields of
the desired carbonylated products in 10–12 h. The carbon-
ylative Suzuki coupling reaction of 2-iodopyridine and 3-
iodopyridine with phenyl boronic acid using Pd/C as a cata-
lyst provides 83% and 87% yield, respectively, of the desired
products (Table 3, Entries 1–2). The reaction of 3-iodopyr-
idine with electron-rich aryl boronic acids such as 2-meth-
ylphenyl boronic acid and 4-methoxyphenyl boronic acid
offer products in admirable yield (86–83%) (Table 3, Entries
3–4). The reaction of 3-iodopyridine with para-bro-
mophenyl boronic acid gave a moderate yield (70%) of the
desired product (Table 3, Entry 5). To our delight, the Pd/
C catalyzed the carbonylative Suzuki coupling reaction of
2-iodothiophene with a variety of phenyl boronic acids to
provide good yields (73–86%) of the desired products
(Table 3, Entries 6–9).
Encouraged by these results, we used Pd/C in the carbon-
ylative Suzuki coupling reactions of 5-iodoindole and 3-
iodoquinoline with different aryl boronic acids. To the best
of our knowledge, there is no general method reported for
the synthesis of sterically hindered heteroaryl ketones from
iodoindole and iodoquinoline through carbonylative Suzuki
cross-coupling. 5-Iodoindole smoothly underwent carbon-
ylative coupling with phenyl boronic acid, providing 83%
yield of the carbonylative Suzuki product (Table 3, Entry
10). The reaction of 5-iodoindole with phenyl boronic acids
bearing electron-donating and electron-withdrawing groups
such as –OCH3 and –Br provided the desired carbonylated
products with good yields (Table 3, Entries 11–12). Re-
markably, the reaction of 3-iodoquinoline with phenyl
boronic acid afforded the desired product in 84% yield
(Table 3, Entry 13). The reaction of 3-methyl phenyl bo-
ronic acid with 3-iodoquinoline went smoothly, producing
79% yield of the anticipated product (Table 3, Entry 14).
It is well known that supported palladium leaches out
into the solvent at high temperature, and the reaction is
catalyzed mainly by this dissolved palladium species.[16b] So,
after completion of the reaction, leaching of palladium in
the solution was checked by using ICP-AES analysis, which
showed only 0.24 ppm of palladium in solution. We can
conclude that no significant leaching of palladium oc-
[a] Reaction conditions: aryl iodide (1 mmol), aryl boronic acid
(1.2 mmol), CO (200 psi), 10% Pd/C (2 mol-%), K2CO3 (3 mmol),
anisole (10 mL), 100 °C, 8 h. [b] Isolated yield.
curred. The reusability of the catalyst was also examined
for the standard reaction of iodobenzene with phenyl bo-
ronic acid. After completion of the reaction, the reaction
ing groups like –CH3 and –OCH3 at the para or even ortho mixture was filtered, the catalyst was washed with distilled
positions gave the desired products in moderate to high water and kept at 200 °C in a furnace for 12 h for activation
yields (Table 2, Entries 11–13). However, the reaction of prior to the next reaction cycle. The Pd/C was found to
Eur. J. Org. Chem. 2010, 6981–6986
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M. V. Khedkar, P. J. Tambade, Z. S. Qureshi, B. M. Bhanage
FULL PAPER
Table 3. Carbonylative Suzuki coupling reaction of heteroaryl io- yield was mainly due to workup loss or handling loss of the
dides with various aryl boronic acids.[a]
catalyst during the successive recycles. When the catalyst
that was lost during the first four recycles was compensated,
we observed 88% yield of the product (see Figure 1, IV*).
It should be noted that the compensated catalyst was taken
from parallel sets of recycling experiments after the 3rd re-
cycle. Thus, the catalyst was successfully recycled, and the
reusability procedure was tested up to four times with con-
sistent results.
Figure 1. Catalyst reusability study. Reaction conditions: iodo-
benzene (1 mmol), phenyl boronic acid (1.2 mmol), CO (200 psi),
10% Pd/C (2 mol-%), K2CO3 (3 mmol), anisole (10 mL), 100 °C,
8 h, GC yield.
Conclusions
We have developed an efficient, heterogeneous and reus-
able catalytic system for the carbonylative Suzuki coupling
reaction of aryl and heteroaryl iodides. The reaction was
optimized with respect to various parameters and could be
used for the carbonylative Suzuki coupling reaction of dif-
ferent aryl boronic acids with a variety of aryl and het-
eroaryl iodides, affording good to excellent yields of the de-
sired products, demonstrating the broad application of the
methodology. Catalyst reusability and Pd leaching were also
examined, and Pd/C was found to be effectively recyclable
for four consecutive cycles without any significant loss in
catalytic activity.
Experimental Section
All the chemicals were obtained from Lancaster (Alfa-Aesar) and
used without further treatment. Amorphous Pd/C (10 wt.-%) was
used for all studies. Optimized yields were based on GC analysis
with a Perkin–Elmer chromatograph (30 mϫ0.32 mm 1D-0.25 μm
1
BP-10). All the products were characterized by H NMR and 13C
NMR spectroscopy (Varian Mercury 300 NMR Spectrometer) and
GC–MS analysis (Shimadzu QP 2010).
[a] Reaction conditions: heteroaryl iodide (1 mmol), aryl boronic
General Experimental Procedure for the Carbonylative Suzuki Reac-
tion of Aryl Iodide: To a 100 mL autoclave were added aryl iodide
(1.0 mmol), aryl boronic acid (1.2 mmol), 10% Pd/C (2 mol-%), an-
isole (10 mL) and K2CO3 (3 mmol). The mixture was first stirred
for 10 min and then flushed with CO; then 200 psi of CO was
taken, and the reaction mixture was heated at 100 °C for 8 h. After
completion of the reaction, the reaction mixture was cooled to
room temperature. The catalyst was filtered, and the residue ob-
acid (1.2 mmol), CO (200 psi), 10% Pd/C (2.5 mol-%), K2CO3
(3 mmol), toluene (10 mL), Time = 10 h, T = 100 °C. [b] Isolated
yields. [c] Reaction time 12 h.
maintain its high activity and selectivity for four consecu-
tive cycles (Figure 1). There was no significant decrease in
yield during the first three cycles; however, the yield de-
creased by up to 80% for the fourth cycle. This decrease in tained was purified by column chromatography (silica gel, 60–
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Pd/C: A Catalyst for Phosphane-Free Carbonylative Suzuki Coupling
120 mesh; petroleum ether/ethyl acetate, 60:80) to afford the desired
carbonylated product. The identity of the products was confirmed
by GC–MS, 1H NMR, 13C NMR and IR spectroscopic techniques.
The purity of the compounds was determined by GC–MS analysis.
2.56, 2.93 Hz, 1 H), 7.45–7.44 (m, 3 H), 7.5–7.47 (d, J = 8.06 Hz,
1 H), 7.57–7.55 (d, JH,H = 7.3 Hz, 1 H), 7.83–7.77 (dd, J = 6.96,
8.8 Hz, 2 H), 8.13 (s, 1 H), 8.93 (br., 1 H) ppm. 13C NMR (CDCl3,
75.43 MHz): δ = 104.14 (CH), 111.21 (CH), 124.15 (CH), 125.41
(CH), 125.99 (CH), 127.19 (C), 128.17 (2CH), 129.57 (C), 129.98
(2CH), 131.76 (CH), 138.45 (C), 139.01 (C), 197 (CO) ppm. MS
(ESI+): calcd. for [M + 1] 222.08; found 222.1.
General Experimental Procedure for the Carbonylative Suzuki Reac-
tion of Heteroaryl Iodide: To a 100 mL autoclave were added het-
eroaryl iodide (1.0 mmol), aryl boronic acid (1.2 mmol), 10% Pd/
C (2.5 mol-%), toluene (10 mL) and K2CO3 (3 mmol). The mixture
was first stirred for 10 min and then flushed with CO; then 200 psi
of CO was taken, and the reaction mixture was heated at 100 °C
for 10–12 h. After completion of the reaction, the reaction mixture
was cooled to room temperature. The catalyst was filtered, and the
residue obtained was purified by column chromatography (silica
gel, 60–120 mesh; petroleum ether/ethyl acetate, 60:80) to afford
the desired carbonylated product. The identity of the products was
(1H-Indol-5-yl)(4-methoxyphenyl)methanone: Table 3, Entry 11.
Yield: 207 mg (83%); solid. IR (KBr): ν = 3262, 2929, 2840, 1624,
˜
1508, 1420, 1308, 1252, 1175, 1116, 1093, 1029, 964, 885, 849, 823,
1
760, 731, 614, 576 cm–1. H NMR (300 MHz, CDCl3, 25 °C): δ =
3.88 (s, 3 H), 6.6 (d, J = 2.2 Hz, 1 H), 6.98–6.95 (d, J = 8.8 Hz, 2
H), 7.26–7.25 (d, J = 2.6 Hz, 1 H), 7.42–7.4 (d, J = 8.4 Hz, 1 H),
7.73–7.7 (d, J = 7 Hz, 1 H), 7.86–7.83 (d, J = 8.8 Hz, 2 H), 8.1 (s,
1 H), 8.9 (br., 1 H) ppm. 13C NMR (CDCl3, 75.43 MHz): δ = 55.5
(CH3), 104.15 (CH), 111.07 (CH), 113.35 (CH), 113.59 (CH),
124.07 (CH), 124.86 (CH), 125.94 (CH), 127.16 (C), 130.19 (C),
131.44 (C), 132.56 (2CH), 138.2 (C), 162.77 (C), 196.67 (CO) ppm.
MS (ESI+): calcd. for [M + 1] 252.09; found 252.1.
1
confirmed by GC–MS, H NMR, 13C NMR and IR spectroscopic
techniques. The purity of the compounds was determined by GC–
MS analysis.
Procedure for Catalyst Recycling: The catalyst obtained after fil-
tration was washed with distilled water (10 mLϫ3) and then with
methanol (5 mLϫ3) to remove any organic material present. The
catalyst was then dried in an oven at 200 °C for 12 h and then used
for the next cycle.
(4-Bromophenyl)(1H-indol-5-yl)methanone:
Table 3,
Entry 12.
Yield: 231 mg (77%); solid. IR (KBr): ν = 3269, 1644, 1595, 1429,
˜
1329, 1284, 1203, 1330, 1284, 1203, 1100, 1067, 1011, 977, 878,
1
841, 773, 754, 729 cm–1. H NMR (300 MHz, CDCl3, 25 °C): δ =
Characterization of Selected Compounds
6.65 (d, J = 2.2 Hz, 1 H), 7.3–7.26 (d, J = 12.46 Hz, 1 H), 7.47–
7.44 (d, J = 8.8 Hz, 2 H), 7.7–7.67 (d, J = 8.4 Hz, 2 H), 7.77–7.73
(d, J = 9.9 Hz, 2 H), 8.09 (s, 1 H), 8.6 (br., 1 H) ppm. 13C NMR
(CDCl3, 75.43 MHz): δ = 104.4 (CH), 111.21 (CH), 124.18 (CH),
125.22 (CH), 125.95 (CH), 126.61 (C), 127.3 (C), 129.46 (C), 131.55
(2CH), 131.47 (2CH), 137.82 (C), 138.46 (C), 196.29 (CO) ppm.
MS (ESI+): calcd. for [M + 1] 299.99; found 300.0.
4-Acetylbenzophenone: Table 2, Entry 8. Yield: 190 mg (85%); so-
lid. IR (KBr): ν = 2920, 2852, 1689, 1657, 1593, 1445, 1402, 1358,
˜
1277, 1072, 963, 931, 845, 795, 698 cm–1. 1H NMR (300 MHz,
CDCl3, 25 °C): δ = 2.66 (s, 3 H), 7.52–7.47 (t, J = 7.5 Hz, 2 H),
7.65–7.59 (t, J = 8.8 Hz, 1 H), 7.82–7.79 (d, J = 8.4 Hz, 2 H), 7.88–
7.87 (d, J = 8.4 Hz, 2 H), 8.07–8.04 (d, J = 8.8 Hz 2 H) ppm. 13C
NMR (CDCl3, 75.43 MHz): δ = 22.71 (CH3), 128.18 (2CH), 128.49
(2CH), 130.05 (2CH), 130.11 (2CH), 132.99 (CH), 136.97 (C),
139.62 (C), 141.36 (C), 195.89 (CO), 197.47 (CO) ppm. MS (70 eV):
m/z (%) = 224 (53), 209 (100), 181 (10), 147 (35), 105 (80), 77 (78),
43 (35).
Phenylquinolin-3-ylmethanone: Table 3, Entry 13. Yield: 206 mg
(84%); solid. IR (KBr): ν = 3052, 2924, 2853, 1649, 1598, 1572,
˜
1493, 1445, 1367, 1290, 1245, 1178, 1122, 935, 911, 860, 759, 726,
1
698 595 cm–1. H NMR (300 MHz, CDCl3, 25 °C): δ = 7.55 (m, 3
H), 7.67–7.5 (dd, J = 7.7, 8.1 Hz, 1 H), 7.87–7.8 (m, 2 H), 7.92–
7.89 (d, J = 8.1 Hz, 2 H), 8.2–8.18 (d, J = 8.43 Hz, 1 H), 8.53 (s,
1 H), 9.33 (s, 1 H) ppm. 13C NMR (CDCl3, 75.43 MHz): δ = 126.55
2-Aminobenzophenone: Table 2, Entry 9. Yield: 163 mg (83%); so-
lid. IR (KBr): ν = 3436, 3318, 3054, 2934, 1626, 1589, 1553, 1479,
˜
1449, 1328, 1303, 1250, 1151, 1025, 938, 912, 745, 703, 645 cm–1. (CH), 127.57 (CH), 128.63 (3CH), 129.15 (C), 129.4 (C), 130.01
1H NMR (300 MHz, CDCl3, 25 °C): δ = 6.1 (br., 2 H), 6.61–6.55 (2CH), 131.85 (CH), 133.06 (CH), 136.95 (C), 138.83 (CH), 149.37
(t, J = 7.9 Hz, 1 H), 6.73–6.7 (d, J = 8 Hz, 1 H), 7.3–7.24 (m, 2
H), 7.46–7.42 (t, J = 5.9 Hz, 1 H), 7.51–7.49 (d, J = 7.3 Hz, 2 H),
7.64–7.61 (d,
(C), 150.29 (CH), 194.81 (CO) ppm. MS (70 eV): m/z (%) = 233
(100), 204 (12), 176 (3), 156 (29), 128 (50), 105 (66), 77 (78), 45
J = 8.1 Hz, 2
H) ppm. 13C NMR (CDCl3, (89).
75.43 MHz): δ = 115.53 (CH), 117.04 (CH), 118 (CH), 128.1
(2CH), 129.13 (2CH), 131.04 (CH), 134.24 (CH), 134.59 (CH),
140.16 (C), 150.99 (C), 199.09 (CO) ppm. MS (70 eV): m/z (%) =
197 (100), 120 (41), 105 (16), 92 (31), 77 (44), 65 (36), 51 (19).
Quinolin-3-yl-m-tolylmethanone: Table 3, Entry 14. Yield: 195 mg
(79%); solid. IR (KBr): ν = 3057, 2917, 1656, 1617, 1596, 1495,
˜
1415, 1368, 1292, 1189, 1039, 788, 758, 588 cm–1. 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 2.42 (s, 3 H), 7.45–7.38 (m, 2 H),
7.67–7.6 (dd, J = 7.3, 7.0 Hz, 1 H), 7.95–7.81 (m, 4 H), 8.23–8.2
(d, J = 8.8 Hz, 1 H), 8.56 (s, 1 H), 9.31 (s, 1 H) ppm. 13C NMR
(CDCl3, 75.43 MHz): δ = 21.14 (CH3), 126.45 (CH), 127.5
(CH),128.3 (CH),129.05 (CH), 130.01 (C), 130.18 (CH), 130.93 (C),
131.8 (CH), 133.76 (CH), 134.61 (C), 138.72 (CH), 138.43 (CH),
138.88 (C), 148.85 (C), 149.94 (CH), 194.82 (CO) ppm. MS (70 eV):
m/z (%) = 247 (100), 232 (81), 218 (7), 204 (6), 156 (30), 128 (57),
119 (78), 101 (40), 91 (75), 75 (19), 65 (34), 51 (14), 45 (27).
Pyridin-3-yl-o-tolylmethanone: Table 3, Entry 3. Yield: 171 mg
(86%); solid. IR (KBr): ν = 2925, 2851, 1729, 1670, 1584, 1463,
˜
1292, 1270, 1190, 1081, 1025, 966, 925, 796, 737, 650 cm–1. 1H
NMR (300 MHz, CDCl3, 25 °C): δ = 2.38 (s, 3 H), 7.46–7.26 (m,
5 H), 8.16–8.14 (d, J = 8.1 Hz, 1 H), 8.81–8.79 (d, J = 6.2 Hz, 1
H), 8.93 (s, 1 H) ppm. 13C NMR (CDCl3, 75.43 MHz): δ = 14.14
(CH3), 119 (CH), 123.59 (CH), 125.47 (CH), 129.01 (CH), 131.13
(CH), 131.48 (C), 133.4 (C), 137.28 (CH), 147.11 (C), 151.31 (CH),
153.12 (CH), 196.81 (CO) ppm. MS (70 eV): m/z (%) = 196 (100),
197 (45), 182 (5), 168 (34), 141 (5), 119 (51), 106 (11), 91 (75), 89
(22), 78 (30), 65 (41), 51 (31), 45 (34).
Acknowledgments
(1H-Indol-5-yl)phenylmethanone: Table 3, Entry 10. Yield: 182 mg
(83%); solid. IR (KBr): ν = 3292, 2923, 2851, 1621, 1607, 1572,
The financial support from the University Grant Commission
(UGC) for providing a Junior Research Fellowship to M. V. K. is
gratefully acknowledged.
˜
1
1431, 1322, 1116, 1092, 957, 880, 734 cm–1. H NMR (300 MHz,
CDCl3, 25 °C): δ = 6.62 (d, J = 2.2 Hz, 1 H), 7.27–7.26 (dd, J =
Eur. J. Org. Chem. 2010, 6981–6986
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6985

M. V. Khedkar, P. J. Tambade, Z. S. Qureshi, B. M. Bhanage
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Received: August 13, 2010
Published Online: November 12, 2010
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